June 9, 2011

Universal Flu Vaccine Shows Promise

The need to create a new flu vaccine annually could be eliminated with a universal influenza vaccine that targets a protein common to all strains of influenza A, which has been able to safely produce an immune response in humans, according to a study published in the journal Vaccine.

If proven effective, it will have major implications for global health.

Two studies were conducted, one at the University of Texas Medical Branch at Galveston (UTMB) and one at Johnson County Clin-Trials in Lenexa, Kansas. Researchers assessed the safety, tolerability and immunogenicity (the induced immune response) of the vaccine candidate VAX102.

Healthy adults between the ages of 18 and 49 were randomly assigned to receive two doses of either vaccine or placebo. The doses range from 0.03 to 10 micrograms.

More systemic reactions occurred for those individuals at the highest doses, while doses of 1 microgram or less were safe.

Some degree of antibody response was seen in all vaccinated individuals. Fourteen days after the second dose of VAX102 vaccine, researchers noted a more than four-fold increase in all groups.

VAX102 targets a protein known as M2e, which is found on the surface of the influenza A virus, and has remained relatively unchanged for the past 100 years.

"The M2e antigen had been completely unchanged from 1918 until the recent pandemic, making it of interest to researchers searching for a target for the immune response to influenza that would be stable over many seasons."

VAX102 contains 4 copies of M2e that is fused into the protein flagellin, which is a TLR5 ligand used as an adjuvant.

The vaccine candidate, unlike traditional flu vaccines that target antigens that change continuously, will not need to be updated annually.

Technology used to produce VAX102 would remove many existing limitations of current influenza vaccines, which include inefficiencies linked to manufacturing due to limited production capability and the inability to change the target antigen when the vaccine does not match the circulating strains.

"As we saw in the 2009 influenza pandemic, there is a great public and global health need for a rapid, scalable model for vaccine production," says lead author Christine B. Turley, M.D., Vice Chair for Clinical Services, Department of Pediatrics and a member of UTMB's Sealy Center for Vaccine Development.

Future studies are needed to determine the degree to which the vaccine may be effective against influenza infection. In addition, to better understand, predict and potentially prevent the adverse reactions noted in the high dosage, scientists will also investigate the durability of the antibody response and assess cytokine responses more closely.

Results from future trials may have VAX102 working as a stand-alone vaccine to prevent influenza A, or it could be used in conjunction with vaccines that target traditional influenza antigens, to help increase efficacy when infection occurs with mismatched strains.

Turley says, "If ultimately proven effective, VAX102 will meet this need and offer a completely new approach to global flu prevention and control."


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